Method of making annular tubes



Aug. 12, 1924. 1,504,653

E. C. TAYLOR METHOD OF MAKING ANNULAR TUBES Filed Nov. 16. 1920 INVENTOR Patented a lz, 1924.

UNITE-D 'sTArnS'P -TENT OFFICE ,nnwnnn' c. TAYLOR, or SPRINGFIELD, MASSACHUSETTS, nssreno'n To THE r151:

RUBBER .oonrm, or cmcornn FALLS, MASSACEITSETTS,JA' oonromTIoN'or uAsSecnUsET s.

METHOD maxme mun-n11. Tunas.

h nation m aiwove t c,- 1920. Serial 116,424,416.

To all whom it may concern:

Be it known that I,

ing the properties of full molded tubes but having an even wall thickness throughout. It has particular reference to a process of making tubes which will expand uniformly and which will have uniform strain-resistin qualities throughout.

at is perhaps the standard method of making inner tubes consists in vulcanizing the tube upon a straight mandrel, removing it from the mandrel, and then joining the 55 ends to form an annular tube. Tubes made accordin to this rocess stretch unevenly under inflation, and especially in the larger sizes, will wrinkle on the inner circumference of the annulus. Ithas been proposed to remedy this difiiculty by vulcanizing the tube in an annular mold instead of on a strai ht mandrel, but tubes made according to this process have not been satisfactory as the wall thickness of the tubeis uneven. I 85 believe that no tubes have been produced which comprise both the even wall thickness of the tubes vulcanized on straight mandrels and the lack of distortion under inflation of tubes vulcanized in an annular mold. The present process is designed to overcome the defects in the old processes and to produce in an economical and effective manner a tube combining the good qualities of prior tubes without their defects.

My invention will now be described in connection with the accompanying drawings in which- Fig. 1 is a diagrammatic view of a machine for forming rubber tubes by the extrusion process;

Fi 2 isra section of the tube produced there y; I

EDWARD C. TA YLOR, a citizen of the United States of Amerlca, re-

Fig. 3 is a plan view of a mold in which the tube may shown partly broken away; and

Fig. 4 is a section on line 4.--4 of Fig. 3. f

' The machine indicated generally at 10 in Fig. 1 may be of the well known type in which rubber is extruded by means of suit- .able pressure mechanism through a die 11 to form a tube 12. Broadly speaking this type of machine has previously been used for making rubber tubes, it bein understood that a suitable mandrel is p aced inside die 11 so that the tube extruded is hollow in form. According to the present process, however, this mandrel is placed eccentrically of the die so that the cross-secbe vulcanized, the mold being 7 tion of the tube will be as shown in Fig. 2

in which one side 13 has a wall thickness greater than the opposite side 14. If desired, the tubing machine may be constructed so as to form a suitable mark on either surface 13 or 14, so that when the tube is later handled the thick or thin ortion of the tube can readily be recogniz It will be understood that to facilitate later handling of the tube soapstone or some equivalent may be applied to the inside of the tube during the extrusion process.

The tube thus formed is cut to the proper length so that when it is bent to form an annulus the ends will be joined as shown at 15 by "a lap-joint or otherwise so-tha't the tube will be of the proper circumference. In this step, of the process, the surface 13 is made the outside circumference of the tube, and surface 14 is made the inside circumference, so that, as will be described, the tube will be of even thickness throughout. In the bending of the straight tube into annular form that portion of the tube which assumes the outer circumference of the annulus is subjected to a greater stretch than that portion of the tube forming the inner circumference for the reason that the outer circumference is of greater length than the inner. By making the thickened portion 13 the outer circumference this stretch will bring the tube to an even thickness throughout.

The vulcanization of the tube is referably performed within an annular mo d containing mold portions 16 and 17 held together by'suitable bolts 18 or other devices. The

' valve 19 by which the tube is to be later inflated is preferably built into place before vulcanization and the annular tube formed as described above expanded into the mold by fluid pressure admitted through this valve. Heat is then applied in any suitable way until vulcanization is completed.

ItWill be seen that a tube constructed as described .abovev will be of even thickness throughout, will be vulcanized in substantially the form in which it is to be in the finished tire, and will have the splice 15 cured at the same time tube, thereby avoiding overcuring of the splice such as was common in tubes vulcanv ized straight and subsequently spliced.-

posite to produce a. tube of Having thus described my invention, I

directly opposite, bending the tube as the body of theform an annulus with the thicker of the tube wall to the outside di the' annulus, expanding the annular tube so formed into an annular mold, and vulcanizing the tube. V

' 2. The method of making annular tubes comprising extruding a tube havin an eccentric b'ore, whereby the wall thic ness on one side is greater than the wall thickness so formed into an annulus with the thicker wall portion on the outer circumference of the annulus, joining the tube ends, and vulcanizing the annular tube so formed while we panded into an annular mold.

3. The method of making annular tubes eomprising'forming a straight tube having the wall thickness on one side sufficiently greater than the wall thickness directly 0 posite to produce a tube of substantial y even Wall thickness when inflated into annular form, joining the ends of the tube to form an annulus with the thicker part of the tube wall forming the outside of the annulus, and 'vulcanizln the tube.

EDWAID C. TAYLOR. 

